Subject: Re: [stella] "Zombie" optimizations From: Thomas Jentzsch <tjentzsch@xxxxxx> Date: Fri, 17 Jan 2003 21:18:46 +0100 |
Christopher Tumber wrote: > This is the code I'm using in Space Instigators to draw the shots. I'm > posting it because it's so different the DCP-Solution maybe it sparks > some ideas... > lda Scanline ;3 Cycles 2 Bytes > sbc DrawnShot_Pos_Y ;3 Cycles 2 Bytes > lsr ;2 Cycles 1 Byte > tax ;2 Cycles 1 Byte > lda Player_Shot_Data_Table,x ;4 Cycles 3 Bytes > sta ENABL ;3 Cycles 2 Bytes > ;17 Cycles - Could be 15 Cycles by removing the lsr and widening the > table Those table based approaches are normally a bit faster than branching. But you have to "waste" a lot of ROM. And then there are bit manipulation routines. How about that: lda Scanline ;3 Cycles 2 Bytes sbc DrawnShot_Pos_Y ;3 Cycles 2 Bytes cmp #4 ;2 Cycles 2 Bytes lda #3 ;2 Cycles 2 Bytes adc #0 ;2 Cycles 2 Bytes sta ENABL ;3 Cycles 2 Bytes 15 Cycles and no table. :-) Have fun! Thomas _______________________________________________________ Thomas Jentzsch | *** Every bit is sacred ! *** tjentzsch at web dot de | ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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